Modular filter elements for use in a filter-in-filter cartridge

ABSTRACT

Disclosed are modular filter-in-filter elements, namely an outer filter element and an inner filter element which may be assembled to form a filter cartridge for use in separation methods and systems. The outer filter element typically functions as a coalescing element and the inner element typically functions as a particulate filter element. The disclosed filter cartridges may be structured for separating water from a hydrocarbon-based liquid fuel as the fuel moves through the cartridge from outside to inside.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part under 35 U.S.C. §120of U.S. application Ser. No. 12,247,502, filed on Oct. 8, 2008, thecontent of which is incorporated herein by reference in its entirety.The present application also is a continuation-in-part under 35 U.S.C.§120 of U.S. application Ser. No. 12/780,392, filed on May 14, 2010,which claims the benefit under 35 U.S.C. §119(e) to U.S. ProvisionalApplication Nos. 61/179,939, filed on May 20, 2009; 61/179,170, filed onMay 18, 2009; and 61/178,738; filed on May 15, 2009, the contents ofwhich are incorporated herein by reference in their entireties.

BACKGROUND

The field of the invention relates to filters such as filter-in-filtercartridges useful for fuel-water separation. In particular, the fieldrelates to a filter-in-filter fuel-water separator and particulatefilters preferably comprising thermoplastic material.

The subject matter of this application relates to U.S. application Ser.No. 12/820,784, filed concurrently herewith on Jun. 22, 2010, publishedas U.S. Published Patent Application No. 2011/0168,621, on Jul. 14,2011, and entitled “TWO STAGE WATER SEPARATOR AND PARTICULATE FILTER”,the content of which is incorporated herein by reference in itsentirety.

Coalescers are used widely to remove immiscible droplets from a gaseousor liquid continuous phase, such as in crankcase ventilation (CV)filtration, fuel water separation (FWS), and oil-water separation. Priorart coalescer designs incorporate the principles of enhanced dropletcapture and coalescence by utilizing graded capture (i.e., decreasingfiber diameter, pore size and/or porosity in coalescing media) or byutilizing thick depth coalescers. Wettability also is recognized asaffecting coalescer performance. (See, e.g., U.S. Pat. No. 6,767,459 andU.S. published Patent Application Nos. 2007-0131235 and 2007-0062887).U.S. Pat. No. 5,443,724 discloses that the media should have a surfaceenergy greater than water in order to improve coalescer performance(i.e., that the media should be preferentially wetted by both coalescingdroplets and continuous phases). U.S. Pat. No. 4,081,373 discloses thatcoalescing media should be hydrophobic in order to remove water fromfuel. U.S. published Patent Application No. 2006-0242933 discloses anoil-mist coalescer in which the filtration media is oleophobic, therebyenabling the fluid mist to coalesce into drops and drain from thefiltration media.

With regard to the removal of water from fuel, there is a need toincrease removal efficiency and to remove smaller droplets than in thepast. This challenge is further magnified by the introduction of newfuels with lower interfacial tensions and different additive packages,than fuels in the past. In particular, ultra low sulfur diesel (ULSD)fuel and biodiesel tend to have lower interfacial tensions (IFT), andtherefore have smaller droplet size and more stable emulsions thanprevious diesel fuel. In fuels with lower interfacial tension, the sizeof dispersed droplets is decreased, making the droplets more difficultto remove. Enhanced coalescence therefore is needed to meet thesechallenges. Improved coalescers that include improved coalescing mediaalso are desirable because they permit the use of a smaller media packin view of improved coalescing efficiency. In fuels with lowerinterfacial tension, the size of droplets is decreased, making thedroplets more difficult to remove.

Traditional fuel-water separators (FWS) tend to be single-stage devicesdesigned to be used upstream of the fuel pump. In traditional FWS, thefilter media is phobic with respect to the dispersed water phase andacts as a barrier. However, traditional FWS tend not to provide adequatewater removal for ULSD fuel and biodiesel with low IFTs (<15 dynes/cm)and low separability (<50%) because their pore size tends to be toolarge to effectively capture the small droplets. As such, a largedroplet size is required for effective capture. This large droplet sizealso is a requirement necessitated by the need to maintain the pressuredrop across the FWS to well below the 1 atmosphere of pressure availablewhen the FWS is use upstream of the fuel pump. Also, even when the meanpore size is sufficiently small, FWS media and fibrous filter media ingeneral possess a maximum pore size so large that excessive amounts ofwater passes through these large pores. In modern high pressure commonrail fuel systems where it is important to remove nearly allnon-dissolved water from fuel passing to the injectors, the amount ofwater that passes through these large pores is unacceptable. Also, inmodern HPCR fuel systems it is often desirable for the fuel waterseparator to be located on the pressure side of the pump, where thefilter is exposed to higher pressures and the size of water droplets ismuch smaller. Traditional two-stage fuel-water coalescers (FWC) aredesigned to be used downstream of the fuel pump and tend to be two-stagedevices for fuel in which the first stage captures the droplets, holdsthem so coalescence can occur, then releases the enlarged drops whichare removed by sedimentation/settling, typically after being blocked bythe second separator stage (where the second separator stage acts as anFWS). Traditional two-stage FWC tend to provide higher removalefficiency than FWS, but tend to have insufficient life, due to pluggingby solids or semisolids. To varying degrees, both FWS and FWC areadversely affected by the presence of surfactants in fuels that lowerinterfacial tension, reduce droplet size, slow down the rate ofcoalescence, stabilize emulsions, and may adsorb onto media and renderit less effective. As such, there is a need for improved fuel-waterseparators that exhibit a high efficiency, low pressure drop, and areminimally affected by low interfacial tension and the presence ofsurfactants.

SUMMARY

Disclosed are modular filter-in-filter elements, namely an outer filterelement and an inner filter element which may be assembled to form afilter cartridge for use in separation methods and systems. The outerfilter element typically functions as a coalescing element and the innerelement typically functions as a particulate filter element and for theseparation of coalesced water drops from the fuel. The disclosed filtercartridges may be structured for separating water from ahydrocarbon-based liquid fuel as the fuel moves through the cartridgefrom outside to inside.

In the disclosed cartridges, the inner filter element is located withinthe outer filter element. The outer filter element includes: (i) anouter pleated filter material where the outer pleated filter materialpreferably is polymeric material (e.g., thermoplastic material) and hasa substantially cylindrical or oval shape; (ii) optionally an innernon-pleated filter material in contact directly or indirectly with theouter pleated filter material at inner pleat tips of the outer pleatedfilter material, wherein the inner non-pleated filter materialpreferably is polymeric material (e.g., thermoplastic material) and hasa substantially cylindrical shape; and (iii) end caps attached toopposite ends of the outer pleated filter material and the innernon-pleated filter material. The inner filter element includes: (i) anouter non-pleated filter material where the outer non-pleated filtermaterial preferably is polymeric material (e.g., thermoplasticmaterial), preferably hydrophobic material, and has a substantiallycylindrical shape; (ii) an inner pleated filter material in contactdirectly or indirectly with the outer non-pleated filter material,wherein the inner pleated filter material preferably is polymericmaterial (e.g., thermoplastic material) and has a substantiallycylindrical shape; and (iii) end caps attached to opposite ends of theouter non-pleated filter material and the inner pleated filter material.The outer filter element and the inner filter element may share one orboth end caps. For example, one or both ends of the filter material ofthe outer element and one or both ends of the filter material of theinner element may be attached to the same end cap.

The outer filter element of the disclosed filter cartridges optionallymay include: (iv) an optional support structure, which typically is aperforated or screen material. In some embodiments of the disclosedfilter cartridges, the support structure is located at the outer face ofthe inner non-pleated filter material of the outer filter element. Forexample, the inner non-pleated filter material may be in indirectcontact with the outer pleated filter material of the outer filterelement at the inner pleat tips via the support structure. In otherembodiments, the support structure is located at the inner face of theinner non-pleated filter material of the outer filter element and theinner non-pleated filter material is in direct contact with the outerpleated filter material. Suitable support structures may include but arenot limited to a tube, a screen, a cage-like structure, and a spring.

The outer filter element comprises outer pleated filter material whichmay include one or more layers of media material referred to as a“nanofiber layer,” which has preferable characteristics for coalescingdroplets of water present in hydrocarbon fuel as the fuel passes throughthe outer pleated filter material. Typically, the nanofiber layer has amean pore size, M, where 0.2 μm≦M≦12.0 μm (preferably 0.2 μm≦M≦10.0 μm,and more preferably 0.2 μm≦M≦8.0 μm, e.g., 0.2, 0.8, 1.2, 1.6, 2.0, 2.4,2.8, 3.2, 3.6, 4.0, 4.4, 4.8, 5.2, 5.6, 6.0, 6.4, 6.8, 7.2, 7.6 or 8.0μm). The media material of the nanofiber layer typically has a maximumpore size M_(M) and typically 1≦M_(M)/M≦3, preferably 1≦M_(M)/M≦2 (e.g.,maximum pore sizes M_(M) may include 3, 6, 9, 12, 15, 18, 21, 24, 27,30, 33, and 36 μm). The media material of the nanofiber layer typicallyincludes fibers where the fibers have a mean diameter of less than about1 μm and in some embodiments between 0.07 μm and 1 μm (preferablybetween 0.15 μm and 1 μm, e.g., 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9,or 1.0 μm). The media material of the nanofiber layer typically includesnonwoven polymeric material (e.g., polyamide material), which may beformed by electroblowing. The media material has a suitablepermeability. A suitable permeability may include a permeability of lessthan about 40 cfm (preferably less than about 30 cfm, more preferablyless than about 20 cfm, e.g., 19, 18, 17, 16, 15, 14, 13, 12, 11, or 10cfm). The nanofiber layer of media material has a desirable thickness asmeasured from upstream to downstream relative to flow through thecartridge (i.e., as measured from outside to inside). Suitablethicknesses include thicknesses between 0.05 and 0.4 mm (preferablybetween 0.1 and 0.3 mm, e.g., 0.10, 0.12, 0.14, 0.16, 0.18, 0.20, 0.22,0.24, 0.26, 0.28, and 0.30 mm). The nanofiber layer of media materialpreferably has a basis weight at least about 10 gsm (or at least 20 gsmor 30 gsm).

In addition to the nanofiber layer of media material of the outerpleated filter material of the outer filter element as described above,the outer pleated filter material may include additional layers of mediamaterial having the same or different characteristics as the nanofiberlayer of media material described above. For example, the outer pleatedfilter material of the outer filter element may include one or moreadditional layers of media material upstream or downstream of the layerof media material described above. In some embodiments, the outerpleated filter material of the outer filter element includes anadditional layer of media material that is upstream of the layer ofmedia material described above, namely an upstream first layer of mediamaterial and a downstream second layer of media material as describedabove. The first layer and the second layer of media material have meanpore sizes M₁ and M₂, respectively, and preferably M₁>M₂. For example,M₁ may be at least about 2.5×, 5×, or 10× greater than M₂ (e.g., M₁≧10μm, M₁≧20 μm, or M₁≧30 μm). The additional layer of upstream mediamaterial may include fibers, where the fibers have an average fiberdiameter of 1-100 μm, 3-100 μm, 10-100 μm, 20-100 μm, or 40-100 μm. Theadditional layer of upstream media material has a suitable permeability.A suitable permeability for the upstream media material may include apermeability of between about 20-500 cfm (preferably between about30-400 cfm, more preferably between about 40-300 cfm, e.g., 50, 75, 100,125, 150, 175, 200, 225, 250, 275, or 300 cfm).

In other embodiments, the outer pleated filter material of the outerfilter element includes an additional layer of media material that isdownstream of the nanofiber layer of media material described above,namely an upstream first layer of media material as described above anda downstream second layer of media material. The first layer and thesecond layer have mean pore sizes M₁ and M₂, respectively, andpreferably M₁<M₂. For example, M₂ may be at least about 2.5×, 5×, or 10×greater than M₁ (e.g., M₂≧10 μM, M₂≧20 μm, or M₂≧30 μm). The additionallayer of downstream media material may include fibers, where the fibershave an average fiber diameter of 1-100 μm, 3-100 μm, 10-100 μm, 20-100μm, or 40-100 μm. The additional layer of downstream media material hasa suitable permeability. A suitable permeability for the downstreammedia material may include a permeability of between about 20-500 cfm(preferably between about 30-400 cfm, more preferably between about40-300 cfm).

In further embodiments, the outer pleated filter material of the outerfilter element may include an additional layer upstream of the least onelayer of media material described above and an additional layer of mediamaterial downstream of the nanofiber layer of media material describedabove, namely an upstream first layer of media material, an interiorsecond layer of media material as described above, and a downstreamthird layer of media material. The first layer, second layer (i.e., amiddle layer or “the nanofiber layer” as described above), and thirdlayer have mean pore sizes M₁, M₂, and M₃, respectively, and preferablyM₁>M₂ and M₃>M₂. For example, M₁ may be at least about 2.5×, 5×, or 10×greater than M₂ and/or M₃ may be at least about 2.5×, 5×, or 10× greaterthan M₂ (e.g., M₁ and/or M₃≧10 μm; M₁ and/or M₃≧20 μm; or M₁ and/orM₃≧30 μm). The additional layers of upstream and downstream mediamaterial may include fibers, which may be the same or different, wherethe fibers have an average fiber diameter of 1-100 μm (preferably 10-100μm, more preferably 20-100 μm). The additional layers of upstream mediamaterial and downstream media material have suitable permeabilities,which may be the same or different. A suitable permeability for theupstream media material and the downstream media material may include apermeability of between about 20-500 cfm (preferably between about30-400 cfm, more preferably between about 40-300 cfm).

Where the outer pleated filter material of the outer filter element is acomposite material (e.g., comprising multiple layers), the mean poresize, M, for the composite material may be determined. Preferably, thecomposite material has a mean pore size, M, where 0.2 μm≦M≦12.0 μm (morepreferably 0.2 μm≦M≦10.0 μm, and even more preferably 0.2 μm≦M≦8.0 μm).Further, the composite material has a maximum pore size M_(M) andtypically 1≦M_(M)/M≦5, preferably 1≦M_(M)/M≦3, more preferably1≦M_(M)/M≦2 (e.g., maximum pore sizes M_(M) may include 3, 6, 9, 12, 15,18, 21, 24, 27, 30, 33, and 36 μm). Preferably, the composite materialhas a permeability of less than about 40 cfm (more preferably less thanabout 30 cfm, even more preferably less than about 20 cfm).

The outer pleated filter material of the outer filter element typicallyfunctions to coalesce droplets of water present in hydrocarbon fuel asthe fuel passes through the outer pleated filter material. Optionally,the outer pleated filter material may comprise slits or holes (e.g.,approximately 30-300 μm in size) that are present in the valleys of thepleats and function as release points for coalesced drops of water.

In a further embodiment, the outer filter element optionally includes aninner non-pleated filter material downstream of the outer pleated filtermaterial that preferably functions as a release layer for coalesceddrops of water as the coalesced drops drain from the outer pleatedfilter material. In some embodiments, the inner non-pleated filtermaterial has a mean pore size, M, where 20 μm≦M≦100 μm (preferably 25μm≦M≦50 μm, and more preferably 30 μm≦M≦40 μm). The inner non-pleatedfilter material typically includes fibers, and preferably the fibershave a mean diameter between 10-100 μm (more preferably between 20-100μm). The inner non-pleated filter material typically includes nonwovenpolymeric material (e.g., polyethylene terephthalate material). Theinner non-pleated filter material has a suitable permeability. Asuitable permeability may include a permeability of between about100-400 cfm (preferably between about 150-250 cfm). The innernon-pleated filter material has a desirable thickness as measured fromupstream to downstream relative to flow through the cartridge (i.e., asmeasured from outside to inside). Suitable thicknesses includethicknesses between about 0.6 and 2 mm (preferably between about 0.8 and1.2 mm).

Referring now to the inner filter element, this element includes anouter non-pleated filter material and an inner pleated filter material(e.g., where the outer non-pleated filter material contacts the innerpleated filter material either directly or indirectly). Preferably, theouter non-pleated filter material of the inner filter element ishydrophobic (e.g., where a drop of water in the hydrocarbon fuel has acontact angle on the outer non-pleated filter material of the innerfilter element that is no less than 90° (preferably no less than 120°,more preferably no less than 135°). Preferably, the outer non-pleatedfilter material of the inner filter element includes a woventhermoplastic mesh or screen (e.g., a mesh or screen having an openingless than 100 μm, and preferably less than 50 μm). The outer non-pleatedfilter material has a suitable permeability (e.g., between about 300-700cfm, and preferably between about 400-600 cfm).

The inner filter element comprises inner pleated filter material.Typically, the inner pleated filter material of the inner filter elementincludes one or more layers of media material and at least one layer ofthe media material has a mean pore size, M, that is less than any meanpore size of any layer of the outer pleated filter material of the outerfilter element (e.g., where 0.2 μm≦M≦6.0 μm, preferably 0.2 μm≦M≦5.0 μm,more preferably 0.2 μm≦M≦4.0 μm, e.g., 0.2, 0.6, 0.8, 1.0, 1.6, 2.2,2.8, 3.4, or 4.0 μm). The media material has a maximum pore size M_(M)and typically 1≦M_(M)/M≦3, preferably 1≦M_(M)/M≦2. Preferably, the mediamaterial of the at least one layer includes fibers having a meandiameter less than about 1 μm (e.g., 1, 0.8, 0.6, 0.4, or 0.2 μm), andpreferably the fibers are nonwoven polymeric material (e.g., polyamidematerial). The media material has a suitable permeability. A suitablepermeability may include a permeability of less than about 40 cfm(preferably less than about 20 cfm, more preferably less than about 15cfm, even more preferably less than about 10 cfm, e.g., 9, 8, 7, 6, 5,or 4 cfm). The at least one layer of media material has a desirablethickness as measured from upstream to downstream relative to flowthrough the cartridge (i.e., as measured from outside to inside).Suitable thicknesses include thicknesses between about 0.05 and 0.4 mm(preferably between about 0.1 and 0.3 mm, e.g., 0.10, 0.12, 0.14, 0.16,0.18, 0.20, 0.22, 0.24, 0.26, 0.28, and 0.30 mm). The at least one layerof media material preferably is nanofiber material having a preferablebasis weight (e.g., at least about 10 gsm, 20 gsm, or 30 gsm).

In addition to the at least one layer of media material of the innerpleated filter material of the inner filter element as described above,the inner pleated filter material may include additional layers of mediamaterial having the same or different characteristics as the at leastone layer of media material described above. For example, the innerpleated filter material of the inner filter element may include one ormore additional layers of media material upstream or downstream of thelayer of media material described above. In some embodiments, the innerpleated filter material of the inner filter element includes anadditional layer of media material that is upstream of the layer ofmedia material described above, namely an upstream first layer of mediamaterial and a downstream second layer of media material as describedabove. The first layer and the second layer of media material have meanpore sizes M₁ and M₂, respectively, and preferably M₁>M₂. For example,M₁ may be at least about 2.5×, 5×, or 10× greater than M₂ (e.g., M₁≧10μm, M₁≧20 μm, or M₁≧30 μm). The additional layer of upstream mediamaterial may include fibers, where the fibers have an average fiberdiameter of 1-100 μm, 3-100 μm, 10-100 μm, 20-100 μm, or 40-100 μm). Theadditional layer of upstream media material has a suitable permeability.A suitable permeability for the upstream media material may include apermeability of between about 20-300 cfm (preferably between about40-300 cfm, more preferably between about 60-300 cfm).

In other embodiments, the inner pleated filter material of the innerfilter element includes an additional layer of media material that isdownstream of the at least one layer of media material described above,namely an upstream first layer of media material as described above anda downstream second layer of media material. The first layer and thesecond layer have mean pore sizes M₁ and M₂, respectively, andpreferably M₁<M₂. For example, M₂ may be at least about 2.5×, 5×, or 10×greater than M₁ (e.g., M₂≧10 μm, M₂≧20 μm, or M₂≧30 μm). The additionallayer of downstream media material may include fibers, where the fibershave an average fiber diameter of 10-100 μm, 20-100 μm, or 40-100 μm.The additional layer of downstream media material has a suitablepermeability. A suitable permeability for the downstream media materialmay include a permeability of between about 20-300 cfm (preferablybetween about 40-300 cfm, more preferably between about 60-300 cfm).

In further embodiments, the inner pleated filter material of the innerfilter element may include an additional layer upstream of the least onelayer of media material described above and an additional layer of mediamaterial downstream of the at least one layer of media materialdescribed above, namely an upstream first layer of media material, aninterior second layer of media material as described above, and adownstream third layer of media material. The first layer, second layer(i.e., a middle layer or “the at least one layer” as described above),and third layer have mean pore sizes M₁, M₂, and M₃, respectively, andpreferably M₁>M₂ and M₃>M₂. For example, M₁ may be at least about 2.5×,5×, or 10× greater than M₂ and/or M₃ may be at least about 2.5×, 5×, or10× greater than M₂ (e.g., M₁ and/or M₃≧10 μm; M₁ and/or M₃≧20 μm; or M₁and/or M₃≧30 μm). The additional layers of upstream and downstream mediamaterial may include fibers, which may be the same or different, wherethe fibers have an average fiber diameter of 1-100 μm, 10-100 μm, 20-100μm, or 40-100 μm. The additional layers of upstream media material anddownstream media material have suitable permeabilities, which may be thesame or different. A suitable permeability for the upstream mediamaterial and the downstream media material may include a permeability ofbetween about 20-500 cfm (preferably between about 30-400 cfm, morepreferably between about 40-300 cfm).

Where the inner pleated filter material of the inner filter element is acomposite material (e.g., comprising multiple layers), the mean poresize, M, for the composite material may be determined. Preferably, thecomposite material has a mean pore size, M, where 0.2 μm≦M≦6.0 μm (morepreferably 0.2 μm≦M≦5.0 μm, even more preferably 0.2 μm≦M≦4.0 μm). M forthe composite material of the inner pleated material of the inner filterelement typically is smaller than M for the composite material of theouter pleated material of the outer filter element. The compositematerial of the inner pleated filter material may have a maximum poresize M_(M) and typically 1≦M_(M)/M≦5, preferably 1≦M_(M)/M≦3, morepreferably 1≦M_(M)/M≦2. Preferably, the composite material of the innerpleated filter material has a permeability of less than about 40 cfm(preferably less than about 20 cfm, more preferably less than about 15cfm, even more preferably less than about 10 cfm, e.g., 9, 8, 7, 6, 5,or 4 cfm).

The outer filter element and the inner filter element of the disclosedcartridges typically include pairs of end caps, which optionally areshared. Typically, the outer pleated material and the optional innernon-pleated material of the outer filter element are attached to the endcaps of the outer filter element at the respective ends of the outerpleated material and the optional inner non-pleated material of theouter filter element. Typically, the outer non-pleated material and theinner pleated material of the inner filter element are attached to theend caps of the inner filter element at the respective ends of the outernon-pleated material and the inner pleated material of the inner filterelement. In some embodiments, the outer filter element and the innerfilter element may share a top or bottom end cap (i.e., where the filtermaterial of the outer filter element and the filter material of theinner filter element both are embedded in the same end cap which may beat the top or the bottom of the filter material). The end caps of theouter filter element and/or the inner filter element may be attached tothe respective ends of the filter material in any suitable manner,including manners that prevent bypass of unfiltered fluid around themedia. Suitable attachments include potting in an adhesive (e.g.,polyurethane) or embedding the ends of the filter media in thermoplasticend caps. Preferably, the end caps of the outer filter element and/orinner filter element comprise polymeric material (e.g., polyurethanematerial). In some embodiments, the end caps comprise metal end capsthat contain polyurethane or other potting adhesive for the filtermaterial.

In some embodiments, the entire filter cartridge is polymeric materialsuch as thermoplastic material. Accordingly, the entire cartridge can berecycled or incinerated, the layers of media material can be bondedtogether more easily where consecutive layers are both thermoplastic,chemical resistance and compatibility for thermoplastic materialtypically is better than other options such as cellulose material, andfurther, media properties such as mean pore size and distribution can bemore easily controlled.

The outer filter element and the inner filter element may be assembledto form a filter cartridge as contemplated herein. The disclosedcartridges may be enclosed in a containment structure such as housingsknown in the art. Suitable housings typically include one or more inletsto receive fluid for filtering and one or more outlets or drains fordischarging filtered fluid (e.g., hydrocarbon liquid) and/or coalesceddrops of a dispersed phase (e.g., water).

The disclosed filter cartridges may be utilized in systems and methodsfor separating a dispersed phase from a continuous phase. In someembodiments, the disclosed filter cartridges may be used in systems andmethods for fuel water separation, including systems and methods forremoving water dispersed in hydrocarbon fuel. The systems and methodsfurther may include or utilize hydrophobic media or an additional devicepositioned downstream of the disclosed cartridges for removingadditional water from the filtered fuel. Additional devices may include,but are not limited to a gravity separator, centrifuge, impactor,lamella separator, inclined stacked plate, screen, water absorber (e.g.,a superabsorbent polymer or hydrogel), and quiescent chamber.Preferably, the disclosed cartridges may be utilized in systems andmethods that are effective for removing at least about 93%, 95%, 97%, or99% of water dispersed in hydrocarbon fuel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates one embodiment of a filter cartridge as contemplatedherein.

FIG. 2 is an exploded view of the embodiment of FIG. 1.

FIG. 3 illustrates a traverse cross-sectional view of the embodiment ofFIG. 1 along 3-3.

FIG. 4 illustrates an exploded view of one embodiment of an outerelement as contemplated herein.

FIG. 5 illustrates an exploded view of one embodiment of an innerelement as contemplated herein.

FIG. 6 illustrates an exploded view of one embodiment of a fuel waterseparator as contemplated herein having an outer element and an innerelement.

FIG. 7 illustrates an exploded view of one embodiment of an outerelement of a fuel water separator as contemplated herein.

FIG. 8 illustrates an exploded view of one embodiment of an innerelement of a fuel water separator as contemplated herein.

FIG. 9 illustrates a cross-sectional view of embodiments of an outerelement of a fuel water separator as contemplated herein showing medialayers and configuration. A. Embodiment without supporting center tubeor screen. B. Embodiment with supporting center tube or screen (7)inside of non-pleated media cylinder (6). C. Embodiment with supportingcenter tube or screen (7) between pleated media (1-5) and non-pleatedmedia cylinders (6).

FIG. 10 illustrates a cross-sectional view of embodiments of an innerelement of a fuel water separator as contemplated herein showing medialayers and configuration.

DETAILED DESCRIPTION

Disclosed are modular filter-in-filter elements, namely an outer filterelement and an inner filter element which may be assembled to form afilter cartridge for use in separation methods and systems. The modularfilter-in-filter elements and filter cartridges assembled therefrom maybe further described as follows.

The outer filter element and inner filter element include or utilizemedia that comprises one or more layers of media material for filteringa mixture of a continuous phase and a dispersed phase and coalescing thedispersed phase. Such media may be referred to herein as “coalescingmedia material.” As contemplated herein, the one or more layers may havea desirable pore size, porosity, and fiber diameter. The one or morelayers may be homogenous (i.e., comprising a single type of material) orheterogeneous (i.e., comprising intermixed materials). The terms “poresize,” “porosity,” and “fiber diameter,” may refer to “average” or“mean” values for these terms (e.g., where the layer is heterogeneous orgraded and “pore size,” “porosity,” and “fiber diameter,” are reportedas mean pore size, average porosity, or average fiber diameter for theheterogeneous layer).

The disclosed cartridges may be utilized in separation methods orsystems for removing a dispersed phase from a continuous phase. In someembodiments, the disclosed cartridges are utilized to separate anaqueous liquid (e.g., water) from a mixture of the aqueous liquiddispersed in hydrocarbon liquid. As contemplated herein, a hydrocarbonliquid primarily includes hydrocarbon material but further may includenon-hydrocarbon material (e.g., up to about 1%, 5%, 10%, or 20%non-hydrocarbon material). Hydrocarbon liquid may include hydrocarbonfuel.

The outer filter element and inner filter element may include media thatis woven or non-woven. Further, the outer filter element and innerfilter element may include media that is polymeric or non-polymeric.Suitable polymeric material may include, but is not limited to polyamidematerial, polyalkylene terephthalate material (e.g., polyethyleneterephthalate material or polybutylene terephthalate material),polyester material, halocarbon material (e.g., Halar® brand ethylenechlorotrifluoroethylene (ECTFE), and polyurethane material. Polymericmaterials may include thermoplastic materials.

The outer filter element and inner filter element may include or utilizemultilayer media. Such media may be formed by melt-blowing two differentlayers of media, one of top of another, by a wet laid process,electrospinning, electroblowing, melt-spinning, ultrasonic bonding,chemical bonding, physical bonding, co-pleating, or other means orcombination.

The outer filter element, inner filter element, and filter cartridgesassembled therefrom may be utilized in filtering and coalescing systemsand methods as known in the art. (See, e.g., U.S. Pat. Nos. 7,527,739;7,416,657; 7,326,266; 7,297,279; 7,235,177; 7,198,718; 6,907,997;6,884,349; 6,811,693; 6,740,358; 6,730,236; 6,605,224; 6,517,615;6,422,396; 6,419,721; 6,332,987; 6,302,932; 6,149,408; 6,083,380;6,056,128; 5,874,008; 5,861,087; 5,800,597; 5,762,810; 5,750,024;5,656,173; 5,643,431; 5,616,244; 5,575,896; 5,565,078; 5,500,132;5,480,547; 5,480,547; 5,468,385; 5,454,945; 5,454,937; 5,439,588;5,417,848; 5,401,404; 5,242,604; 5,174,907; 5,156,745; 5,112,498;5,080,802; 5,068,035; 5,037,454; 5,006,260; 4,888,117; 4,790,947;4,759,782; 4,643,834; 4,640,781; 4,304,671; 4,251,369; 4,213,863;4,199,447; 4,083,778; 4,078,965; 4,052,316; 4,039,441; 3,960,719;3,951,814; and U.S. published Application Nos. 2009-0020465;2009-0134097; 2007-0289915; 2007-0107399; 2007-0062887; 2007-0062886;and 2007-0039865; the contents of which are incorporated herein byreference in their entireties.) The coalescing media disclosed hereinmay be manufactured utilizing methods known in the art and may includeadditional features disclosed in the art. (See, e.g., patents andpublished application references above and U.S. Pat. Nos. 6,767,459;5,443,724; and 4,081,373; and U.S. published Patent Application Nos.2007-0131235; 2007-0062887; and 2006-0242933; the contents of which areincorporated herein by reference in their entireties).

The disclosed filter cartridges assembled therefrom may be utilized forremoving a dispersed phase (e.g., water) from a continuous phase (e.g.,hydrocarbon fuel). For example, the filter cartridges assembled may beutilized for removing a dispersed phase from a continuous phase where atleast about 93, 95, 97, or 99% of the dispersed phase is removed fromthe continuous phase after the phases are passed through the cartridges.

The coalescing media described herein may comprise material havingdistinct hydrophilicity or hydrophobicity, or distinct oleophilicity oroleophobicity. In some embodiments, the coalescing media comprises alayer of material comprising relatively hydrophobic material, relativeto the dispersed phase of the mixture. In some embodiments, the outerfilter element and the inner filter element comprise one or more layersof media material that are hydrophobic. The property of hydrophobicityof a media material may be accessed by measuring a contact angle (θ) ofa dispersed phase (e.g., water) in a continuous phase (e.g., hydrocarbonfuel) on the media material.

Referring now to FIGS. 1-5, shown is one embodiment of an outer filterelement 4, inner filter element 6, and filter cartridge 2 assembledtherefrom. The outer element 4 includes pleated filter media 4 a in acylindrical shape in direct or indirect contact with a non-pleatedcylinder of media 4 b at the inner pleat tips of the pleated cylinder.The pleated and non-pleated cylinders are bonded, potted, embedded, orotherwise attached at their ends to endcaps (4 c, top end cap, and 4 e,bottom end cap) located at opposite ends of the cylinders. The top endcap 4 c optionally includes a gasket 4 d. The non-pleated cylinder 4 bmay be directly or indirectly in contact with the inner pleat tips ofthe pleated cylinder 4 a. Typically, the distance between the inner tipsof the pleated section and the non-pleated cylinder is such that thereis no significant gap or separation between the tips and the cylinder.The inner element 6 includes outer non-pleated filter media 6 a in acylindrical shape in direct or indirect contact with an inner pleatedcylinder of media 6 b. As such, the inner element's configuration (i.e.,outer non-pleated filter media and inner pleated filter media) is incontrast to the outer filter element's configuration (i.e., outerpleated filter media and inner non-pleated filter media). Thenon-pleated and pleated cylinders of the inner element are bonded,potted, embedded or otherwise attached at their ends to endcaps (6 c,top end cap, and 6 d, bottom end cap) located at opposite ends of thecylinders.

Referring now to FIGS. 6-8, shown is one embodiment of a thermoplasticfilter-in-filter fuel water separator (FWS) and particulate filter ascontemplated herein. FIG. 9 shows cross-sectional views embodiments ofthe outer element of the presently disclosed, filter-in-filter fuelwater separator (FWS) and particulate filter. FIG. 9A shows anembodiment without a center tube, screen or other supporting structurefor the media of the outer element. FIG. 9B shows an embodiment with acenter tube, screen or other supporting structure for the media locateddownstream of and adjacent to the non-pleated media cylinder. FIG. 9Cshows an embodiment with a center tube, screen or other supportingstructure for the media located between, adjacent to, and touching boththe upstream pleated media cylinder and the downstream non-pleated mediacylinder. In FIG. 9, the numerals 1-5 indicate, in order from upstreamto downstream, the different layers of media of the pleated mediacylinder. The numeral 6 indicates the non-pleated media and 7 indicatesthe structure, e.g., center tube, screen, spring, etc., that supportsthe media of the outer element. As shown, the pleated cylinder comprisesthree layers of thermoplastic, fibrous filter media (Layers 1-3), onelayer of thermoplastic nanofiber media (Layer 4), and a final layer ofthermoplastic, fibrous media (Layer 5). The non-pleated cylindercomprises a layer of thermoplastic fibrous media (Layer 6) formed as atube and placed inside the pleated media cylinder with its upstream faceeither in direct contact with the pleated media cylinder or in indirectcontact with the pleated media cylinder via the intermediary supportingstructure (7), as shown. The optional supporting structure (7) mayfunction to prevent the non-pleated cylinder from collapsing under flowand pressure drop when the cartridge is used in a fuel water separationsystem. However, preferably the pleated and non-pleated cylinderstogether provide sufficient strength and stiffness rendering thesupporting structure optional. In FIG. 9C, the supporting structureprovides support to the pleated cylinder, whose inner pleat tips are indirect contact with the supporting structure, while the non-pleatedcylinder is located inside, downstream of, and in direct contact withthe support structure. In some embodiments, the non-pleated cylinder maybe thermally welded to or injection molded with the thermoplastic centertube to affix it to the support structure. Typically, the axial lengthsof all 7 layers are the same. Both ends of each of the cylinders areeither embedded into endcaps or potted in an adhesive, e.g.,polyurethane, to attach the ends of the cylinders to the endcaps andprevent bypass of unfiltered fluid around the media during use in a fuelwater separation system (FIGS. 1-8).

The outer element of FIGS. 9B and 9C includes 6 layers of media materialand a supporting structure. However, the outer element may include feweror additional layers depending on the requirements of the system inwhich the filter cartridge is utilized. For illustrative purposes only,three coalescers referred to as X, Y, and Z are described in Table 1including the typical properties of each layer of media of thesecoalescers.

TABLE 1 Exemplary Media Layers and Properties for Outer Stage NominalMean Mean Fiber Pore Max Pore Basis Diameter Size Size PermeabilityThickness Weight Layer Material (μm) (μm) (μm) (cfm) (mm) (gsm)Coalescer X - Velocity Change Coalescer 1 Polybutylene terephthalateNonwoven >10 >50   >100 >250 >0.3 >40 ± 5  2 Polybutylene terephthalateNonwoven 1.0-4.0  5.0-15.0 10.0-20.0 35-55  0.7-0.15 27 ± 5 3Polybutylene terephthalate Nonwoven 1.0-5.0 15.0-30.0 25.0-40.0  75-1000.15-0.3  33 ± 5 4 Polyamide Nonwoven 0.1-1.0 <8.0  5.0-15.0  5.0-20.0 0.1-0.25 >20 5 Polyethylene terephthalate Nonwoven >40 20.0-40.0 40-6050-75 0.4-0.7 198 ± 20 6 Polyethylene terephthalate Nonwoven >20 25-4540-60 150-200 0.8-1.2 100 ± 20 Coalescer Y - Single Layer SurfaceCoalescer 4 Polyamide Nonwoven 0.1-1.0 <8.0  5.0-15.0  5.0-20.0 0.1-0.25 >20 5 Polyethylene terephthalate Nonwoven (optional) >4020.0-40.0 40-60 50-75 0.4-0.7 198 ± 20 6 Polyethylene terephthalateNonwoven >20 25-45 40-60 150-200 0.8-1.2 100 ± 20 Coalescer Z - SurfaceCoalescer 3 Polybutylene terephthalate Nonwoven 1.0-5.0 15.0-30.0 25-40 75-100 0.15-0.3  33 ± 5 4 Polyamide Nonwoven 0.1-1.0 <8.0  5.0-15.0 5.0-20.0  0.1-0.25 >20 5 Polyethylene terephthalate Nonwoven(optional) >40 20-40 40-60 50-75 0.4-0.7 198 ± 20 6 Polyethyleneterephthalate Nonwoven >20 25-45 40-60 150-200 0.8-1.2 100 ± 20

The media combinations of these three coalescers reflect design choicesbased on the observation that in low interfacial tension systems, suchas ULSD and biodiesel, there is relatively little thermodynamic drivefor coalescence and the kinetics of coalescence tend to be slow. Thesecoalescers are designed to physically slow down the passage of dropletsof a dispersed phase in a continuous phase (e.g., dispersed droplets ofwater in hydrocarbon fuel) through the media and to increase theconcentration of the droplets locally within the coalescer in order tofacilitate coalescence and drop size growth.

In Coalescer X, at least 6 media layers with an optional supportingstructure are used. Coalescer X may be referred to as a “velocity changecoalescer” (see PCT Publication No. WO 2010/042706, which isincorporated by reference herein in its entirety) having afilter-in-filter configuration (see USPTO Publication Nos. US2009/0065419; US 2009/0250402; and US 2010/0101993, which areincorporated by reference herein in their entireties). Layer 1 functionsas a pre-filter and to reduce the pressure drop across the outerelement. Layer 1 is more “open” (i.e., having a higher porosity, largerpore size, larger mean fiber diameter, higher Frasier permeability,and/or lower contaminant removal efficiency) than Layer 2. Layer 2functions to capture fine emulsified droplets, for example waterdroplets in ultralow sulfur diesel fuel. Layer 2 is “tighter” (i.e.,having a lower porosity, smaller pore size, smaller mean fiber diameter,lower Frasier permeability, and/or higher contaminant removalefficiency) than Layer 3. Layer 3 functions to reduce the fluid velocitywithin the media and provide a space for droplets captured in Layer 2 todrain, accumulate, and coalesce. The physical properties of Layer 3 aresuch that the fluid velocity in this layer is less than the fluidvelocity in Layer 4. Layer 3 is more “open” (i.e., having a higherporosity, larger pore size, larger mean fiber diameter, higher Frasierpermeability, and/or lower contaminant removal efficiency) than Layer 4.Layer 4 functions to capture droplets that were not captured by theprevious layers, especially the finer droplets, and to serve as asemi-permeable barrier to the passage of captured droplets. Thesemi-permeable barrier function of Layer 4 causes droplets toconcentrate and accumulate in Layer 3, giving the droplets more time andgreater probability for coalescence to occur. The semi-permeable barrierfunction of Layer 4 also gives rise to localized increased fluidvelocity and a transient increase in drop surface area, which furtherenhances coalescence. The physical properties of Layer 4 are such thatthe fluid velocity in this layer is higher than the fluid velocity inLayer 5. Layer 4 is “tighter” (i.e., having a lower porosity, smallerpore size, smaller mean fiber diameter, lower Frasier permeability,and/or higher contaminant removal efficiency) than Layer 5. Layer 4typically is thermoplastic nanofiber filter media with a diameter ofless than 1 μm (e.g., in order to achieve the very high water removalefficiency requirements and to accommodate the small droplet size formodern high pressure common rail diesel fuel systems running of ULSD orbiodiesel). Layer 5 functions to create a lower velocity environment inwhich the coalesced drops formed in the previous layers may collect anddrain through prior to release. Layer 5 is more “open” (i.e., having ahigher porosity, larger pore size, larger mean fiber diameter, higherFrasier permeability, and/or lower contaminant removal efficiency) thanLayer 4. Layer 6 functions to provide release sites for coalesced dropsin a low energy environment. Layer 6 is more “open” (higher porosity,larger pore size, larger mean fiber diameter, higher Frasierpermeability, and/or lower contaminant removal efficiency) than Layer 5.

In Coalescer Y, two or three layers of media are utilized with orwithout an optional supporting structure. Coalescer Y may be referred toas a “single layer surface coalescer” (see USPTO Application Ser. No.61/178,738, filed on May 15, 2009 and USPTO application Ser. No.12/780,392, filed on May 14, 2010, and published as USPTO PublicationNo. 2011/0124941, which are incorporated herein by reference in theirentireties) having a filter-in-filter configuration (see USPTOPublication Nos. US 2009/0065419; US 2009/0250402; and US 2010/0101993,which are incorporated by reference herein in their entireties). InCoalescer Y, Layer 4 functions to provide a semi-permeable barrier tothe passage of fine emulsified droplets, forcing them to concentrate atits upstream surface. As such, droplets have sufficient time and asuitable environment for coalescence and drop growth to occur. Layer 4is a relatively “tight” layer with characteristics comparable to Layer 4in Coalescer X or even tighter. This layer utilizes “sieving” to preventpassage of fine droplets and typically comprises thermoplastic nanofiberfilter media with a mean pore size, M, smaller than the mean size of theinfluent droplets and a maximum to mean pore size ratio of less than 3(i.e., M_(M)/M≦3. In some embodiments, a water drain is present on theupstream face of the outer element through which drops coalesced at theupstream surface of Layer 4 drain, while in other embodiments, there maybe a water drain present on the downstream side of the outer element tocollect coalesced water that has been forced through the media atrelease sites by the pressure drop across the coalescing element.Coalescer Y has an optional Layer 5 to provide structural support forLayer 4, if required, and to serve as a drainage path for any coalesceddrops forced through Layer 4. Layer 5 connects Layer 4 to the releaseLayer 6. Layer 5 also functions to create a lower velocity, lower energyenvironment in which the coalesced drops formed in the previous layersmay collect and drain through prior to release. Layer 5 is more “open”than Layer 4 and is structurally stronger, in order to provide supportto Layer 4 and to facilitate processing of the media. Coalescer Y has anadditional non-pleated Layer 6 downstream of the previously describedLayer 4 and Layer 5. Layer 6 functions to provide release sites forcoalesced drops in a low energy environment. As such, Layer 6 is more“open” than Layer 5.

In Coalescer Z, three or more media layers with an optional supportingstructure are utilized (see USPTO Application Ser. No. 61/179,170, filedon May 18, 2009; USPTO Application Ser. No. 61/179,939, filed on May 20,2009; and USPTO application Ser. No. 12/780,392, filed on May 14, 2010,and published as USPTO Publication No. 2011/0124941, which areincorporated herein by reference in their entireties). Coalescer Z is amore complex surface coalescer than Coalescer Y and has afilter-in-filter configuration (see USPTO Publication Nos. US2009/0065419; US 2009/0250402; and US 2010/0101993, which areincorporated by reference herein in their entireties). Layer 3 functionsto reduce the pressure drop across the coalescer and, secondarily, toserve as a particulate prefilter for the coalescer and to increase itsservice life. Layer 3 is more “open” than Layer 4 and has a highercapillary pressure (i.e., a more positive capillary pressure) than Layer4. The function and properties of Layers 4, 5 (optional) and Layer 6 areas described for Coalescer Y.

In all three coalescers X, Y, and Z, the nature of the transition fromLayer 5 to Layer 6 is important. Layers 1-5 typically are pleated. Assuch, the fluid flow profile within the pleat and drag on captured dropscauses them to accumulate in the valleys (downstream direction) of thepleats. This results in droplets concentrating in this localized region,increasing coalescence by providing increased time for drops to coalescebefore they are released. It has been observed by the present inventorsthat coalesced drops tend to be released from the same active regions orareas on the downstream face of coalescers, while little drop releaseoccurs elsewhere. This suggests that once a drainage path through themedia is created, it is repeatedly used. In the presently disclosedfilter cartridges, preferred drainage paths ending in larger pores arecreated by the direct contact of the inner pleat tips of Layer 4 (forCoalescers Y and Z) or Layer 5 (for Coalescer X, as well as, Y and Z ifthis layer is included) to the upstream surface of non-pleated Layer 6.At the point of contact between the pleated and non-pleated layers, alocalized disruption of the media pore structure exists which gives riseto these preferred drainage paths. This results in larger drops beingreleased. Further, these drainage paths occur at the bottoms of pleatvalleys where coalesced drops concentrate and the effect is greatest.Direct contact between Layers 4 or 5, and Layer 6 is not required inorder to achieve this result. For example, the inner pleat tips of themost downstream layer of the pleated section may directly contact theporous supporting structure 7, which is in turn in direct contact withLayer 6 on its downstream side, as shown in FIG. 9C.

In an additional embodiment (not illustrated), the pleated coalescermedia could be as described in Coalescers X, Y or Z, except that Layer6, the non-pleated release layer, would be omitted. This configurationutilizes the same fluid flow profile within the pleat and drag oncaptured drops effects as Coalescers X, Y or Z, to cause droplets andcoalesced drops to concentrate in the valleys of the pleats to enhancecoalescence. Instead of coalesced drops draining to a release layer,Layer 6, however, drops are released from small slits or holes 10 in theinner pleat tips. (See FIG. 7), These slits or holes 10 could beproduced by needle punching or other means and may be on the order of30-300 μm in size. These slits or holes 10 in the inner pleat tips serveas release points for the coalesced drops.

The inner element of the presently disclosed filter cartridge functionsto separate coalesced water drops from the fuel and to remove fine solidcontaminants from the fluid. The inner element comprises an outernon-pleated cylinder in direct contact with an inner pleated cylinder.Typically, the axial lengths of both non-pleated and pleated cylindersare the same. Both ends of each of the cylinders are either embeddedinto endcaps or potted in an adhesive, e.g., polyurethane, to attach theends of the cylinders to the endcaps and prevent bypass of unfilteredfluid around the media during use in a fuel water separation system(FIGS. 1-8).

The inner element typically includes of at least 4 layers of mediamaterial (FIG. 10). The purpose of the first layer, Layer A, is toseparate coalesced (water) drops from the continuous phase (fuel). Thislayer preferably comprises a woven thermoplastic mesh in the form of atube that repels the drops and allows them to drain freely from thesurface. Layer A is outside of and in direct contact with the innerpleated cylinder. The mesh opening of this layer typically is less than100 μm and preferably less than 50 μm. The function of the pleatedlayers is to capture solid contaminants and droplets not removed by theupstream layers of the outer filter element. The first two of thesepleated layers, Layers B and C in FIG. 10 and Table 2, are transitionallayers which function to reduce pressure drop, to provide furtherremoval of drops and droplets, and to reduce solids from collecting onthe following nanofiber filtration layer, Layer D. Layer B alsofacilitates manufacturing and processing of the composite material.

TABLE 2 Exemplary Media Layers and Properties of Inner Stage NominalMean Mean Fiber Pore Max Pore Basis Diameter Size Size PermeabilityThickness Weight Layer Material (μm) (μm) (μm) (cfm) (mm) (gsm) APolyethylene terephthalate Woven Screen * 30-50 30-50 400-600 0.03-0.1 37 ± 10 B Polybutylene terephthalate Nonwoven >10 >50 >100 225-3250.3-0.5 48 ± 10 C Polybutylene terephthalate Nonwoven 1.0-5.0  5.0-15.010.0-25.0 35-55 0.1-0.3 38 ± 10 D Polyamide Nonwoven 0.1-0.8 1.0-8.0 1.0-10.0  3.0-20.0 0.1-0.3 >20 E Polyethylene terephthalateNonwoven >40 20-35 40-65 50-75 0.45-0.65 198 ± 20 

These layers have properties similar to Layers 1 and 2 in the outerelement. The next pleated layer, Layer D in FIG. 10 and Table 2,functions as a high efficiency filter for fine particles (e.g.,particles having diameter of 4 μm or smaller). For high pressure commonrail applications, very high removal efficiencies for particles as smallas 4 μm typically are required to protect the fuel injectors. The layersupstream of Layer D function primarily to remove and separate droplets.Layer D functions to protect the downstream system from beingcontaminated by fine solids. Layer D also functions to remove dropletsthat may have passed through the preceding layers. Preferably, Layer Dis “tighter” than any of the other layers of the outer element or theinner element and includes thermoplastic nanofiber filter media with adiameter of less than 1 μm. Minimally, Layer D of the inner element isas “tight” as Layer 4 of the outer element. The final layer, Layer E,functions to provide support for the preceding layers withoutsignificantly increasing the pressure drop. Layer E is a relatively“open” media having sufficient strength and stiffness to support theupstream layers under conditions of use and to facilitate processing ofthe inner element media.

In the foregoing description, certain terms have been used for brevity,clearness, and understanding. No unnecessary limitations are to beimplied therefrom beyond the requirement of the prior art because suchterms are used for descriptive purposes and are intended to be broadlyconstrued. The different configurations, systems and method stepsdescribed herein may be used alone or in combination with otherconfigurations, systems and method steps. It is to be expected thatvarious equivalents, alternatives and modifications are possible. Theafore-cited patents and published applications are incorporated hereinby reference in their entireties.

What is claimed is:
 1. A filter cartridge structured for coalescing adispersed phase from a mixture of the dispersed phase in a continuousphase as the mixture moves through the cartridge from outside to inside,the cartridge comprising: (a) an outer filter element, the outer filterelement comprising: (i) an outer pleated filter material where the outerpleated filter material has a substantially cylindrical shape andcomprises thermoplastic composite material having a permeability of lessthan about 40 cfm, wherein the composite material is formed from atleast the following layers: (1) a top layer comprising a polymericnonwoven, the top layer having a mean fiber diameter of >10 μm, the toplayer having a higher porosity, a larger pore size, a larger mean fiberdiameter, a higher Frasier permeability, and a lower contaminant removalefficiency than a layer immediately downstream of the top layer; (2) ananofiber layer comprising a polymeric nonwoven, the nanofiber layerhaving a mean fiber diameter of 0.1-1.0 μm, the nanofiber layer having amean pore size of <8 μm; and the nanofiber layer having a maximum tomean pore size ratio of less than about 3; and (3) a support layercomprising a polymeric nonwoven, the support layer having a mean fiberdiameter of >20 μm, the support layer having a larger pore size, alarger mean fiber diameter, a higher Frasier permeability, and a lowercontaminant removal efficiency than a layer immediately upstream of thesupport layer; (ii) end caps attached to opposite ends of the outerpleated filter material; and (b) an inner filter element located withinthe outer filter element; the inner filter element comprising: (i) anouter non-pleated filter material where the outer non-pleated filtermaterial has a substantially cylindrical shape; (ii) an inner pleatedfilter material in contact directly or indirectly with the outernon-pleated filter material, wherein the inner pleated filter materialhas a substantially cylindrical shape and comprises thermoplasticcomposite material having a permeability of less than about 20 cfm,wherein the composite material is formed from: (1) a top layercomprising a polymeric nonwoven, the top layer having a mean fiberdiameter of >10 μm, the top layer having a higher porosity, a largerpore size, a larger mean fiber diameter, a higher Frasier permeability,and a lower contaminant removal efficiency than a layer immediatelydownstream of the top layer; (2) a nanofiber layer comprising apolymeric nonwoven, the nanofiber layer having a mean fiber diameter of0.1-1.0 μm, the nanofiber layer having a mean pore size of <8 μm; andthe nanofiber layer having a maximum to mean pore size ratio of lessthan about 3; and (3) a support layer comprising a polymeric nonwoven,the support layer having a mean fiber diameter of >20 μm, the supportlayer having a larger pore size, a larger mean fiber diameter, a higherFrasier permeability, and a lower contaminant removal efficiency than alayer immediately upstream of the support layer; and (iii) end capsattached to opposite ends of the outer non-pleated filter material andthe inner pleated filter material.
 2. The cartridge according to claim1, wherein the outer filter element further comprises: (iii) an innernon-pleated filter material in contact directly or indirectly with theouter pleated filter material at inner pleat tips of the outer pleatedfilter material, wherein the inner non-pleated filter material has asubstantially cylindrical shape and the end caps are attached toopposite ends of the inner non-pleated filter material.
 3. The cartridgeaccording to claim 2, wherein the inner non-pleated filter material ofthe outer filter element comprises polymeric material.
 4. The cartridgeaccording to claim 3, wherein the polymeric material is thermoplasticmaterial.
 5. The cartridge according to claim 2, wherein the entirecartridge is polymeric material.
 6. The cartridge according to claim 5,wherein the polymeric material is thermoplastic material.
 7. Thecartridge according to claim 2, wherein the outer filter element furthercomprises: (iv) a support structure selected from a group consisting ofa permeable tube, a screen, a spring, a cage-like structure, wherein thesupport structure contacts the inner non-pleated material of the outerfilter element.
 8. The cartridge according to claim 7, wherein thesupport structure is located at the inner face of the inner non-pleatedfilter material of the outer filter element and the inner non-pleatedfilter material directly contacts the outer pleated filter material ofthe outer filter element at the inner pleat tips.
 9. The cartridgeaccording to claim 7, wherein the support structure is located at theouter face of the inner non-pleated filter material of the outer filterelement and the inner non-pleated filter material indirectly contactsthe outer pleated filter material of the outer filter element at theinner pleat tips via the support structure.
 10. The cartridge accordingto claim 1, wherein the outer pleated filter material of the outerfilter element has slits or holes in valleys of the pleated filtermaterial.
 11. The cartridge according to claim 1, wherein the outernon-pleated filter material of the inner filter element comprisespolymeric material.
 12. The cartridge according to claim 11, wherein thepolymeric material is thermoplastic material.
 13. The cartridgeaccording to claim 1, wherein the entire cartridge is polymericmaterial.
 14. The cartridge according to claim 13, wherein the polymericmaterial is thermoplastic material.
 15. The cartridge according to claim1, wherein the nanofiber layer comprises polyamide material.
 16. Thecartridge according to claim 1, wherein the outer pleated filtermaterial is formed by physically or chemically coupling the top layer,the nanofiber layer, and the bottom layer.
 17. The cartridge accordingto claim 1, wherein the outer pleated filter material is formed byelectroblowing a media material and combining the electroblown mediamaterial and another media material in layers.
 18. The cartridgeaccording to claim 1, wherein the cartridge is configured for coalescingwater dispersed in a continuous phase of hydrocarbon fuel.
 19. Thecartridge according to claim 18, wherein the outer non-pleated filtermaterial of the inner filter element is hydrophobic.
 20. The cartridgeaccording to claim 18, where a drop of water in the hydrocarbon fuel hasa contact angle on the outer non-pleated filter material of the innerfilter element that is no less than 90°.
 21. The cartridge according toclaim 1, wherein the end caps comprise polymeric material.
 22. Thecartridge according to claim 21, wherein the polymeric material isthermoplastic material.
 23. The cartridge according to claim 1 containedin a housing, the housing having an upstream inlet structured to receivethe mixture, a downstream outlet structured to discharge the mixtureafter coalescing of the dispersed phase, and a downstream outletstructured to discharge the coalesced dispersed phase.
 24. A fuel waterseparation system comprising the cartridge according to claim
 1. 25. Thefuel water separation system according to claim 24, structured forremoving water dispersed in hydrocarbon fuel.
 26. The fuel waterseparation system according to claim 24, further comprising ahydrophobic media for removing water positioned downstream of thecartridge.
 27. The fuel water separation system according to claim 24,further comprising an additional device for removing water positioneddownstream of the filter cartridge, the device selected from a groupconsisting of gravity separator, centrifuge, impactor, lamellaseparator, inclined stacked plate, screen, water absorber, and quiescentchamber.
 28. The cartridge according to claim 1, wherein the outerfilter element further comprises a permeable tube, a screen, a spring,and a cage-like structure downstream of the outer pleated filtermaterial.
 29. A method of removing water dispersed in hydrocarbon fuel,the method comprising passing a mixture comprising hydrocarbon fuel andwater dispersed in the hydrocarbon fuel through the filter cartridge ofclaim 1 and removing at least about 95% of water dispersed in thehydrocarbon fuel.
 30. A thermoplastic filter-in-filter cartridgecomprising an outer filter element and an inner filter element, theouter filter element comprising: (a) an outer pleated filter materialwhere the outer pleated filter material has a substantially cylindricalshape and comprises thermoplastic composite material, and wherein thecomposite material is formed from at least the following layers: (1) atop layer comprising a polymeric nonwoven, the top layer having a meanfiber diameter of >10 μm, the top layer having a higher porosity, alarger pore size, a larger mean fiber diameter, a higher Frasierpermeability, and a lower contaminant removal efficiency than a layerimmediately downstream of the top layer; (2) a nanofiber layercomprising a polymeric nonwoven, the nanofiber layer having a mean fiberdiameter of 0.1-1.0 μm, the nanofiber layer having a mean pore size of<8 μm; and the nanofiber layer having a maximum to mean pore size ratioof less than about 3; and (3) a support layer comprising a polymericnonwoven, the support layer having a mean fiber diameter of >20 μm, thesupport layer having a larger pore size, a larger mean fiber diameter, ahigher Frasier permeability, and a lower contaminant removal efficiencythan a layer immediately upstream of the support layer; (b) end capsattached to opposite ends of the outer pleated filter material; and (c)optionally one of: (i) an inner non-pleated filter material in contactdirectly or indirectly with the outer pleated filter material at innerpleat tips of the outer pleated filter material, wherein the innernon-pleated filter material has a substantially cylindrical shape andthe end caps are attached to opposite ends of the inner non-pleatedfilter material; and (ii) slits or holes in valleys of the pleatedfilter material; and the inner filter element comprising: (a) an outernon-pleated filter material where the outer non-pleated filter materialhas a substantially cylindrical shape; (b) an inner pleated filtermaterial in contact directly or indirectly with the outer non-pleatedfilter material, wherein the inner pleated filter material has asubstantially cylindrical shape and comprises thermoplastic compositematerial; and wherein the composite material is formed from at least thefollowing layers: (1) a top layer comprising a polymeric nonwoven, thetop layer having a mean fiber diameter of >10 μm, the top layer having ahigher porosity, a larger pore size, a larger mean fiber diameter, ahigher Frasier permeability, and a lower contaminant removal efficiencythan a layer immediately downstream of the top layer; (2) a nanofiberlayer comprising a polymeric nonwoven, the nanofiber layer having a meanfiber diameter of 0.1-1.0 μm, the nanofiber layer having a mean poresize of <8 μm; and the nanofiber layer having a maximum to mean poresize ratio of less than about 3; and (3) a support layer comprising apolymeric nonwoven, the support layer having a mean fiber diameterof >20 μm, the support layer having a larger pore size, a larger meanfiber diameter, a higher Frasier permeability, and a lower contaminantremoval efficiency than a layer immediately upstream of the supportlayer; and (c) end caps attached to opposite ends of the outernon-pleated filter material and the inner pleated filter material. 31.The cartridge according to claim 30, wherein the outer filter elementfurther comprises a permeable tube, a screen, a spring, and a cage-likestructure downstream of the outer pleated filter material.
 32. A filterelement comprising: (a) an outer pleated filter material where the outerpleated filter material has a substantially cylindrical shape andcomprises thermoplastic composite material; (b) end caps attached toopposite ends of the outer pleated filter material; and optionally oneof: (i) an inner non-pleated filter material in contact directly orindirectly with the outer pleated filter material at inner pleat tips ofthe outer pleated filter material, wherein the inner non-pleated filtermaterial has a substantially cylindrical shape; and (ii) slits or holesin valleys of the pleated filter material; wherein the compositematerial is formed from at least the following layers: (1) a top layercomprising a polymeric nonwoven, the top layer having a mean fiberdiameter of >10 μm, the top layer having a higher porosity, a largerpore size, a larger mean fiber diameter, a higher Frasier permeability,and a lower contaminant removal efficiency than a layer immediatelydownstream of the top layer; (2) a nanofiber layer comprising apolymeric nonwoven, the nanofiber layer having a mean fiber diameter of0.1-1.0 μm, the nanofiber layer having a mean pore size of <8 μm; andthe nanofiber layer having a maximum to mean pore size ratio of lessthan about 3; and (3) a support layer comprising a polymeric nonwoven,the support layer having a mean fiber diameter of >20 μm, the supportlayer having a larger pore size, a larger mean fiber diameter, a higherFrasier permeability, and a lower contaminant removal efficiency than alayer immediately upstream of the support layer.
 33. The filter elementaccording to claim 32, wherein the filter element is an outer filterelement structured for use in a filter-in-filter cartridge.
 34. Thefilter element according to claim 32, further comprising a permeabletube, a screen, a spring, and a cage-like structure downstream of theouter pleated filter material.
 35. A filter element comprising: (a) anouter non-pleated filter material where the outer non-pleated filtermaterial has a substantially cylindrical shape and comprisesthermoplastic hydrophobic material; (b) an inner pleated filter materialin contact directly or indirectly with the outer non-pleated filtermaterial, wherein the inner pleated filter material has a substantiallycylindrical shape and comprises thermoplastic composite material; and(c) end caps attached to opposite ends of the outer non-pleated filtermaterial and the inner pleated filter material; wherein the compositematerial is formed from at least the following layers: (1) a top layercomprising a polymeric nonwoven, the top layer having a mean fiberdiameter of >10 μm, the top layer having a higher porosity, a largerpore size, a larger mean fiber diameter, a higher Frasier permeability,and a lower contaminant removal efficiency than a layer immediatelydownstream of the top layer; (2) a nanofiber layer comprising apolymeric nonwoven, the nanofiber layer having to mean fiber diameter of0.1-1.0 μm, the nanofiber layer having a mean pore size of <8 μm; andthe nanofiber layer having a maximum to mean pore size ratio of lessthan about 3; and (3) a support layer comprising a polymeric nonwoven,the support layer having a mean fiber diameter of >20 μm, the supportlayer having a larger pore size, a larger mean fiber diameter, a higherFrasier permeability, and a lower contaminant removal efficiency than alayer immediately upstream of the support layer.
 36. The filter elementaccording to claim 35, wherein the filter element is an inner filterelement structured for use in a filter-in-filter cartridge.